A medical observation apparatus used for surgery, for example, a microscope for surgery has an important role to improve an efficiency of the surgery by enlarging and observing a surgical site by an operator (observer) such as a doctor at the time of the surgery.
As such a microscope for surgery, a stereomicroscope which can image a stereoscopic image has been widely used in recent years. For example, two imaging optical systems are provided in the stereomicroscope, and a stereoscopic image and video are obtained by using a parallax (for example, refer to Patent Document 1).
In the surgery using the medical observation apparatus, an operation has been widely performed in which an optical image enlarged by the stereomicroscope is photoelectrically converted by an image pickup element and an image and a video are projected on a display and stereographically observed. It is desirable that the image projected on the display have a high resolution. Therefore, it is required to improve an image quality and a resolution for the optical system.
The image quality of a television and a camera have been significantly improved in recent years. A high-resolution television camera system formed by combining a single-plate camera having over eight million pixels with a television having a resolution of about 2000 TV lines has been proposed. In an operation site for surgery and the like, the high-resolution television camera system has been desired to extend a procedure and improve safety. In this case, a resolution exceeding 2000 TV lines is required for the stereomicroscope optical system of the medical observation apparatus.